How can I change the backgroudColor ofselectedItem in recyclerView adapter when I use android databinding?
this is my Adapte,and class CategoyItemClickListener is implemened for handling item clicks :
class ProgramCatAdapter(
val mContext: Context,
val mData: MutableList<CategoryResponse>,
val clickListener: CategoyItemClickListener
) : RecyclerView.Adapter<ProgramCatAdapter.CategoryViewHolder>() {
override fun onCreateViewHolder(
parent: ViewGroup,
viewType: Int
): CategoryViewHolder {
return CategoryViewHolder.from(parent)
}
override fun getItemCount(): Int {
return mData.size
}
override fun onBindViewHolder(holder: CategoryViewHolder, position: Int) {
holder.bind(
mData[position],
clickListener,
position
)
}
fun getItem(position: Int): CategoryResponse = mData[position]
fun getPosition(item: CategoryResponse): Int = mData.indexOf(item)
class CategoryViewHolder private constructor(val binding: ProgramCatHorizontalBinding) :
RecyclerView.ViewHolder(binding.root) {
fun bind(
item: CategoryResponse,
clickListener: CategoyItemClickListener,
position: Int
) {
itemView.isActivated = isSelected
binding.item = item
binding.position = position
binding.clickListener = clickListener
binding.executePendingBindings()
}
companion object {
fun from(parent: ViewGroup): CategoryViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
val binding = ProgramCatHorizontalBinding.inflate(layoutInflater, parent, false)
return CategoryViewHolder(binding)
}
}
}
}
class CategoyItemClickListener(val clickListener: (item: CategoryResponse) -> Unit) {
fun onClick(item: CategoryResponse) {
clickListener(item)
}
}
And this code is for binding adapter to recyclerView :
private fun bindCategories(cats: MutableList<CategoryResponse>?) {
programCatAdapter = ProgramCatAdapter(mContext!!,
cats!!, CategoyItemClickListener {
viewModel.setSelectedCat(it)
})
binding.catRecycler.layoutManager =
LinearLayoutManager(activity!!, LinearLayoutManager.HORIZONTAL, false)
binding.catRecycler.adapter = programCatAdapter
}
How can I have access to the position of selected Item from CategoyItemClickListener and change the bgColor of that item?
Here an example:
This video might give you an overview: https://youtu.be/g8GDLOMt600 (You are not going to find a solution for this question in this video. It just gives you a nice overview about data binding, RecyclerView and ClickListener)
You need the following files: YourFragment, fragment_your.xml, list_item
class YourFragment : Fragment(){
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Get a reference to the binding object and inflate the fragment views.
val binding: FragmentYoutFragmentBinding = DataBindingUtil.inflate(
inflater, R.layout.fragment_your, container, false
)
binding.lifecycleOwner = this
// Very important! Otherwise the layout of the recycler view wont work
binding.yourList.layoutManager = LinearLayoutManager(this.context)
// Adapter for the RecyclerView in order to show all items
val adapter = YourAdapter(YourListener{youtItemObeject: YourItemObject, view:
View ->
// THIS IS THE SOLUTION
// change selected item image, if user selects this item in the list
view.ok_image.setImageResource(R.drawable.ok_green)
})
}
}
in list_item.xml
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools">
<data>
<variable
name="your_object"
type="your_package_name.your_folder.YourObject" />
<variable
name="clickListener"
type="your_package_name.your_folder.YourListener" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:id="@+id/constraint_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="@dimen/item_margin_horizontal"
android:layout_marginTop="@dimen/item_margin_vertical"
android:layout_marginEnd="@dimen/item_margin_horizontal"
android:layout_marginBottom="@dimen/item_margin_vertical"
android:onClick="@{(thisView) -> clickListener.onClick(your_object, thisView)}">
<ImageView
android:id="@+id/ok_image"
... />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
And add YourListener class into the adapter-File
class YourAdapter(val clickListener: YourListener) :
ListAdapter<YourObject, YourAdapter.ViewHolder>(YourDiffCallback()) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder.from(parent)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.bind(getItem(position)!!, clickListener)
}
class ViewHolder private constructor(val binding: ListItemYourObjectBinding) :
RecyclerView.ViewHolder(binding.root) {
companion object {
fun from(parent: ViewGroup): ViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
val binding =
ListItemYourObjectBinding.inflate(layoutInflater, parent, false)
return ViewHolder(binding)
}
}
fun bind(item: YourObject, clickListener: YourListener) {
binding.yourObject = item
binding.clickListener = clickListener
// for example
binding.okImage.setImageRessouce(R.drawable.ok_gray)
binding.executePendingBindings()
}
}
}
/**
* Callback for calculating the diff between two non-null items in a list.
*
* Used by ListAdapter to calculate the minimum number of changes between and old list
* and a new list that's been passed to `submitList`.
*/
class YourObjectDiffCallback : DiffUtil.ItemCallback<YourObject>() {
override fun areItemsTheSame(oldItem: YourObject, newItem: YourObject): Boolean {
return oldItem.yourObjectValue == newItem.yourObjectValue
}
override fun areContentsTheSame(oldItem: YourObject, newItem: YourObject): Boolean {
return oldItem == newItem
}
}
/**
* Listener for your list items
*/
class YourListener(val clickListener: (yourObject: YourObject,
view: View) -> Unit) {
fun onClick(yourObject: YourObject, view: View) =
clickListener(yourObject, view)
}